Development of Novel Techniques for Evaluating Physical, Chemical and Toxicological Properties of Particulate Matter in Ambient Ai

There has been a large body of epidemiological and toxicological studies indicating the strong associations between exposures to ambient particulate matter (PM) and adverse health outcomes. Some specific chemical component in ambient PM, including but not restricted to airborne transition metals, has been hypothesized to be mostly responsible for generating excess cellular oxidation stress and eventually result in PM induced health risks. Due to the complex physical property and chemical composition of ambient PM, assessing which PM constituents are linked to adverse health outcomes as well as the exact mechanisms leading to these outcomes remains an active topic of research. Therefore, novel technologies for characterizing ambient PM with high time resolutions are in great needs, which will assist in investigations of the physical properties and chemical composition of PM, as well as enabling a better understanding of toxicological properties of ambient PM.;This dissertation focuses on the development and evaluations on novel techniques in determining the physical, chemical and toxicological properties of ambient PM. As the first part of this dissertation, a two-stage particle concentration enrichment system was developed to provide highly concentrated particles at low flow rate (i.e. 1.5 L/min). This system can enrich particle concentration by a factor roughly of 100-120 without altering their physical and chemical properties. Secondly, as a principle investigation of the new PM collection technology, the relative contributions of water-soluble and water-insoluble portions of ambient PM to cellular redox activity were investigated. Results from this study indicated that both water-soluble and water-insoluble portions of PM played important roles in influencing potential cellular toxicity. Next, a novel Aerosol-Into-Liquid Collector was developed to provide concentrated slurries of fine and/or ultrafine PM, in which both water-soluble and water-insoluble components were well preserved in the collected slurry samples. This new aerosol collection system could achieve an excellent collection efficiency (over 90%), and has the unique ability to be continuously operated unattended for at least 4 to 5 days without any obvious shortcomings in its operation. Following the successfully development of Aerosol-Into-Liquid Collector, this new PM sampler was further developed into a novel monitor for online, in-situ measurement of copper (Cu) in ambient fine PM. Evaluations of the Cu monitor indicates a very good agreement for total and water-soluble Cu concentrations obtained online by this monitor, with measurements performed by inductively coupled plasma mass spectrometry (ICP-MS) as a reference method, suggesting the excellent performance of this Cu monitor in aspect of collection efficiency and measurement accuracy. This technology is then extended to coarse PM by utilizing two virtual impactors combined with a modified liquid impinger (BioSampler) as PM collector. Lastly, a prototype atmospheric aerosol monitor was developed and evaluated for online measurement of other three toxicologically relevant redox-active metals (Fe, Mn, and Cr) in ambient PM2.5 based on the developed instrument described in the previous parts of this dissertation.;The novel techniques developed in this dissertation will greatly advance the capabilities of atmospheric pollution monitoring to understand the physical properties, as well as the chemical and toxicological active components of ambient PM. Moreover, such technologies will provide significant insights on developing a better understanding of the sources, formation mechanisms, and transport of PM in the atmosphere. Ultimately, air pollution monitoring goals can be more directly linked with the protection of public health. More effective and targeted control strategies to better protect human health can thus be implemented.